1. Field of the Invention
This invention relates generally to the art of radiation hardening objects, particularly spacecraft structures and equipment, against damage from momentary exposure to high energy electromagnetic radiation in the form of high energy optical (laser) and nuclear radiation. The invention relates more particularly to radiation hardened structures and equipment and a radiation hardening method utilizing fibrous silica refractory composite material as a radiation barrier or shield.
2. Prior Art
As will appear from the ensuing description, the principles of this invention may be utilized to radiation harden virtually any object against damage from momentary exposure to high energy electromagnetic radiation. The invention is intended primarily for radiation hardening spacecraft against high energy optical radiation, that is high energy laser radiation, and will be described in this context.
High energy lasers are a weapon of the future, if not the present, which will have or now have the capability of seriously damaging if not totally destroying spacecraft. External spacecraft appendages, such as antennas and solar arrays are especially vulnerable to damage or destruction, by laser beams. A variety of radiation shielding techniques for this purpose have been devised. Among these are the following techniques for hardening parabolic antennas against optical radiation, that is laser beams.
Painting the parabolic antenna dish with highly reflective material. This hardening technique is effective only for low intensity laser beams.
Covering the entire antenna including the parabolic reflector dish and the antenna feed with a high energy radiation blanket-shield constructed of high temperature resistant cloth, such as that marketed under the trade mark Astro-Quartz. A cover of this kind having the required opacity to high energy optical radiation or laser beams is relatively heavy and, in addition, severely attenuates and distorts the RF signal transmitted from and received by the antenna.
Providing a laser beam opaque radome over the antenna. This radome has the same disadvantages as the astro-quartz shield above.
Constructing the antenna of high temperature resistant material, such as titanium. This would result in a very heavy antenna structure and high antenna fabrication costs.
The radiation hardening techniques devised for other spacecraft structures and equipment are similarly deficient. Accordingly, a definite need exists for an improved radiation hardening technique for spacecraft, spacecraft systems and equipment, and other objects susceptible to damage or destruction by high level optical and nuclear radiation.